In a brief telephone interview with AFP, Stoltenberg said the attacks would only strengthen the resolve of supporters of democracy who will ultimately win the fight because they have "superior values."
Islamic State jihadists yesterday claimed a series of coordinated attacks by gunmen and suicide bombers in Paris that killed nearly 130 people in scenes of carnage at a concert hall, restaurants and the national stadium.
"The important thing now is to underline how much we condemn the atrocities and the attacks on innocent people in Paris last night," Stoltenberg said after his office proposed the interview to AFP and other media.
"The attack is not only an attack on innocent people in Paris and on France but it is also one on our core values of freedom and democracy and our open societies," according to the NATO secretary general.
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"The aim of this horrific terrorist attack is to scare and intimidate us but this will only strengthen our resolve," the former Norwegian prime minister added.
"We will continue to stay vigilant, determined and united in our defence of democracy and open societies," he said.
"It will take time, but we will win because our values are superior to (those) the extremists are standing for," the head of the North Atlantic Treaty Organisation said.
He also said Muslims are now leading the fight against the Islamic State group, also known as ISIL, in the Middle East and north Africa as they have suffered most of the casualties.
"So this is not a fight between the Islamic world and the western world. This is a fight between extremists, criminals and people who believe in the fundamental values of freedom and the respect for human rights," he said.